JPS5987230A - 2-cycle engine - Google Patents

Abstract

PURPOSE:To form a strong turbulence in a cyinder for improving combustion and fuel consumption of an engine by providing a controlling valve in a predetermined position ranging from a crank chamber through a throttle section to the middle portion of an auxiliary chamber to reduce sufficiently or completely shut off freah air amount flowing from the crank chamber into the auxiliary chamber only in a certain partial load region of the engine. CONSTITUTION:An auxiliary chamber 9 is provided which communicates through a controlling valve 7 to a crank chamber 3. The controlling valve 7 is mechanically interocked with a throttle valve 5, the effective section of the controlling valve 7 being fully opened or approximately fully closed only in a certain partial region such as low load region of an engine to bring to a nill or sufficiently reduce a fresh air amount flowing from the crank chamber 3 into the auxiliary chamber 9. Thus, pressure P in the crank chamber 3 at the beginning of scavenging is raised by one corresponding to the volume of the auxiliary chamber 9 so that the injection speed of fresh air injected from a scavenging path 4 becomes high to provide a strong turbulence formed in a cylinder 2 for improving combustion and the fuel consumption of the engine.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a two-stroke engine having an auxiliary chamber communicating with a crank chamber through a throttle section.

In such an engine, in a partial load region such as a low load region, the pressure in the crank chamber at the start of scavenging becomes extremely low, so the jetting speed of fresh air from the scavenging passage into the cylinder becomes very small, causing the cylinder to The turbulence that forms within the combustion chamber becomes weak and tends to impede combustion.

The present invention is intended to solve these drawbacks and will be described below with reference to the drawings.

In order to understand the present invention, first, a two-stroke engine having the auxiliary chamber will be explained.

In FIG. 1, an auxiliary chamber 9 is provided which communicates with the crank chamber 3 via a throttle section 8 (formed in the control valve 7 itself). (The description will be made assuming that the throttle section 8 and the auxiliary chamber 9 are in complete communication with each other at all times.)

When the scavenging passage 4 is closed during the upward stroke of the piston 1, fresh air is sucked into the crank chamber 3, and then the piston 1
When the engine moves to the downward stroke, the fresh air sucked into the crank chamber 3 is compressed while flowing into the auxiliary chamber 9 while being throttled by the throttle part 8.
In this case, even if the amount of fresh air taken into the crank chamber 3 is the same, the higher the engine rotational speed, the more the piston 1 It is clear that the vehicle has a decreasing proportion of the amount of fresh air flowing into the auxiliary chamber 9 during the downward stroke.

That is, if the pressure inside the crank chamber 3 when the scavenging passage 4 is opened is P, this P becomes higher in the higher speed range of the engine.

Therefore, in the low speed range of the engine, since the above-mentioned P is low, the jetting speed of fresh air jetted out from the scavenging passage 4 becomes small, the scavenging action is performed slowly, and the loss of passing fresh air is significantly reduced. At the same time, pumping loss (loss of work of compressing fresh air in the crank chamber 3) is also reduced.

Thus, the fuel efficiency of the engine is significantly improved.

In the high speed range of the engine, the pressure P is sufficiently high as before, so a good scavenging effect is performed and a decrease in torque can be prevented (in this case, since the engine is in the high speed range, the pressure P is Even if it is high, there is almost no loss of fresh air passing through.)

In the medium speed range of the engine, P has an intermediate value, which simultaneously satisfies both a significant reduction in fresh air passing loss and prevention of torque drop.

In the above-mentioned two-cycle engine, the pressure P in the crank chamber 3 when the scavenging passage 4 is opened by the piston 1 (at the start of scavenging) is extremely low in a certain partial load range such as a low load range. It is conceivable that the turbulent flow formed in the cylinder 2 becomes so weak that the combustion is adversely affected.

In order to solve these drawbacks, the present invention is equipped with a control valve 7 (rotary valve type) that mechanically interlocks with the throttle valve 5, so that the throttle valve is controlled only in a certain partial load region such as a low load region of the engine. 8 (formed on the control valve 7 itself) is fully closed or almost fully closed (that is, the control valve 7 is fully closed or almost fully closed - the figure shows the fully closed state), and the crank chamber 3 The amount of fresh air flowing into the auxiliary chamber 9 from the engine is either completely eliminated or sufficiently reduced (the figure shows the engine in an idling state, and the control valve 7 Needless to say, it is fully opened).

Therefore, since the pressure P in the crank chamber 3 at the start of scavenging increases by an amount corresponding to the volume of the auxiliary chamber 9, the velocity of fresh air ejected from the scavenging passage 4 increases, and the fresh air is formed in the cylinder 2. The resulting turbulence becomes more powerful, improving combustion and increasing engine fuel efficiency.

The control valve 7 can be opened and closed by interlocking it with the throttle valve 5, or by using a diaphragm device (not shown) that operates by sensing the negative pressure in the intake passage 10 downstream of the throttle valve 5. The control valve 7 is fully closed or almost fully closed only in a certain partial load range of the engine (for example, low load range)
That is, it is also possible to consider a method in which the effective cross section of the throttle section 8 is completely closed or almost completely closed.

In this case, if the negative pressure outlet of the diaphragm device is arranged at the position indicated by 5' as indicated by the two-dot chain line (2), then the throttle valve 5 passes the negative pressure outlet 5' and the diaphragm device ( Since atmospheric pressure (approximately) is introduced, the control valve 7 immediately becomes fully open.

The control valve 7 is provided at a position corresponding to the throttle section 8, but if the control valve 7 is removed and a new throttle section fixed at this position is installed, the control valve 7 will be located in the auxiliary chamber 9 as shown by the two-dot chain line ■. A control valve 7' is provided in the middle.

(In the figure, this control valve 7' is a plate valve type similar to the throttle valve 5, and is configured so that it is almost fully closed when the engine is idling.) In Figure 2, the auxiliary chamber 9 is The present invention is implemented in a two-cycle engine that communicates with the crank chamber through two throttle parts, and only in a partial load range such as a low load range of the engine, the throttle part 11 (formed in the control valve 7 itself) (i.e., the control valve 7 is fully closed or almost fully closed) to sufficiently reduce the amount of fresh air flowing from the crank chamber 3 into the auxiliary chamber 9. (the constriction section 12 always has a fixed and constant effective cross-sectional area).

Therefore, since the pressure P in the crank chamber 3 at the start of scavenging increases, the turbulent flow formed in the cylinder becomes stronger as described above, improving combustion and improving the fuel efficiency of the engine.

It goes without saying that the control valve 7 is fully open in the high engine load range.

Since the present invention is configured as described above, the turbulent flow formed in the cylinder becomes strong, combustion is improved, and the fuel efficiency of the engine is improved.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view of a two-stroke engine according to the present invention, and FIG. 2 is a partial cross-sectional view of the two-cycle engine according to the present invention. 1 is a piston, 2 is a cylinder, 3 is a crank chamber, 4 is a scavenging passage, 5 is a throttle valve, 6 is a gas regulator, 7 and 7' are control valves,
8, 11, and 12 are throttle parts, 9 is an auxiliary chamber, 10 is an intake passage, and 5' is a negative pressure outlet. Patent applicant Shuichi Kitamura

Claims (2)

[Claims] (1) In a crank chamber compression type two-stroke engine, an auxiliary chamber is formed, and the auxiliary chamber is communicated with the crank chamber through a constriction part, and this auxiliary chamber is also communicated with a predetermined position on the inner wall of the cylinder. In addition, a control valve is provided at a predetermined position from the crank chamber to the middle of the auxiliary chamber via the throttle section to control the flow of fresh air from the crank chamber to the auxiliary chamber only in a certain region of the partial load range of the engine. A two-stroke engine, characterized in that the control valve is controlled so that the amount of inflow is sufficiently reduced or is not at all. (2) A two-cycle engine according to claim 1, wherein a throttle portion is formed in the control valve.